Electric switch



une 9, 1931. A. w. G. TUCKER 1,80

ELECTRIC SWI TCH Filed Dec. 21, 1923 3 Sheets-Sheet l June 9, 1931. A. w. G. TUCKER ELECTRIC SWITCH Filed Dec. 21, 1923 5 Sheets-Sheet 2 June 9, 1931. A. w. s. TUCKER ELECTRIC SWITCH Filed Dec. 21, 1923 3 Sheets-Sheet 3 Patented June 9, 1931 UNITED STATES PATENT OFFICE ALFRED WILLIAM GEORGE TUCKER, OF HOLLINW'OOD, ENGLAND, ASSIGNOR T0 FER- RANTI, LIMITED, 01: HOLLINWOOD, LANCASTER, ENGLAND ELECTRIC SWITCH Application filed December 21, 1923, Serial No.

ture that means be provided whereby thetapping switch cannot inadvertently be left .in such a position that connection to the transformer winding remains broken.

The invention consists briefly in an electric switch including a series of contacts mounted upon a base, a longitudinally displaoeable and rotatable contact blade, means constantm ly-urging said blade towards said contacts and means ensuring correct registration between the contact blade and the fixed contacts.

Referring to the accompanying diagrammatic drawings Figure 1 represents a longitudinal sectional view of a convenient construction of tap v switch for single phase use;

Figure 2 is a lateral sectional view thereof;

Figures 3 and 4 are views similar to Figures 1 and 2 respectively of a modified construction;

Figures 5, 6 and 7 represent respectively elevational, longitudinal sectional and lateral sectional views of a further modification for three-phase use.

The invention will now be described in one form as illustrated in Figures 1 to 3 applied by way of example to a tapping switch for a three-phase transformer.

A circular base a of insulating material is provided and furnished with, say, six equidistantly spacedfixed contact fingers b, the contacts of any adjacent pair being capable of being connected together at will by means of a movable connectiondescribed below.

This movable connection comprises two contact fingers c, 0, disposed radially and carried rigidly upon a spider cl, the latter being slidably and rotatably supported upon a cen- 682,103, and in Great Britain January 6, 1923.

tral stub spindle e secured to the switch base a. Concentric with the stub spindle is an hexagonal cup-shaped member m, rigidly secured to the base, this member being slotted longitudinally so as to constitute six pillars standing outwards from the face of the base.

The spider "is formed with two diametral radial lugs of such width as to slide within any opposite pair of slots in the cup m and the strong compression spring is serves constantly to urge the spider (1 towards the cup m. The cup m is so positioned relatively to the fixed contacts I) which lie around it that when the spider and cup lie together the bridging contact blades 0, 0 rest in contact with an adjacent pair of contact fingers. The ends of the spider lugs which lie facing the fixed contacts I), b and the corresponding ends of the cup pillars are bevelled to form blunt knife edges for reasons explained below. The spider d is connected mechanically to an operating handle 9 by means of a tube f of insulating material, e. g., by means of split collars n and tangential clamping bolts 0.

Certain of the contacts 6 are coupled to various tapping points on a transformer so that in order to change the tapping it is merely necessary to remove the padlock p securing the hinged handle cover q, to pull out the handle 9 to rotate and then to release the same.

The cover q cannot be closed and padlocked until the switch has been closed completely; thus if by any chance the spring strength should weakenqr the contact surfaces become roughened the effect of closing the cover ensures that the switch is pushed into full engagement. A safe indication that the switch is closed at any time is thus afforded by oba servation of the cover 9.

The blunt knife edges referred to prevent the switch being left in an open condition and ensure correct alignment between the contact fingers 0, 0 and the fixed contacts 6, b; the knife edge surfaces are mutually inclined at an angle of about 90.

According to the modification illustrated in Figures 3 and 4 a similar construction is depicted except that in this case a central con- V locating an operating handle.

cured to the spider an operating shaft it (Figure 1) bearing on each of its ends a universal joint j (Figure 1) this avoids the necessity for exact alignment of the axes of the operating handle and stub spindle.

It will be noted with reference to Figures 1 and 3 that not until the spider has been withdrawn practically to its fullest extent, i. e. with its lugs carried beyond the extremities of the cup pillars, can the handle be rotated.

Any number of switches may be employed and in the case, say, of a three-phase transformer three switches operated simultaneous 1y from a common point may be provided.

According to an exampleof this arrangement illustrated in Figures 5 to 7 three switches are mounted with their axes in line and provided with universal joints between each switch and between the top switch and Thus a single operating'handle g eflects'simultaneous movement of the three switch spiders (Z in this case.

Obviously, a single compression ortension spring in of suflicient strength maybe employed instead of three separate springs.

- The switch contact bases a, a, a in this case are mounted upon tubes 10, w, 10, of metal or of insulating material whichare secured to bosses w, as, 03. These bosses are swivelably mounted between checks 2,, 1 1y, carried on pillars z, z, 2, so that the spider spindles and cups m, m, m, are rendered selfaligning.

In order to effect the nal movement of the switch spiders prior to their rotation a lever 25 in addition to the torsion handle 9 may be provided, this lever acting upon a collar u borne by the operating handle spindle o. 7

It will be understood thaj r according to this invention the'actual changing of connections by the switch involves merely a longitudinal movement of the operating spindle (to overcome the spring pressure) and then a rotary movement of the spindle to select the required connection, followed finally by a release-and longitudinal return movement of the operating spindle. 7

Having now described my invention what I claim as new and desire to secure by a Letters Patent is An electric switch including a series of contacts mounted upon a base, a spindle, a

longitudinally displaceable and rotatable necessary longitudi- Inc 

